1. irrational number
⑴ Irrational number: infinite cyclic decimal.
(2) The sum of two irrational numbers is still irrational.
2. Square root
(1) arithmetic square root, square root
Positive numbers have two square roots, and 0 has only one square root, which is 0 itself; Negative numbers have no square root.
⑵ Square root: The operation of finding the square root of a number is called square root.
radicand
3. Cubic root
⑴ Cubic root, if the cube of a number X is equal to A, that is, then this number X is called the cube root of A. 。
The cube root of a positive number is positive, the cube root of a negative number is negative, and the cube root of 0 is 0.
(3) Number of issuers and customers
4. How wide is this park?
Find the root formula, estimate the root formula, and find the side length according to the area.
5. Real number operation
Arithmetic (addition, subtraction, multiplication, division, multiplication, root)
Algorithm (five plus [multiplication] commutative law, associative law; Distribution law of multiplication to addition)
Operation sequence: a. Advanced operation to low-level operation; B. (Operation at the same level) From "Left"
To the "right" (such as 5 ÷× 5); C (when there are brackets) from "small" to "medium" to "large".
6. The concept of real number is a compulsory knowledge point in the senior high school entrance examination every year, especially the reciprocal, reciprocal and absolute values are all high-frequency test sites. We not only require the inverse of a number, the reciprocal of a number and the absolute value of a number; Also note that 0 has no reciprocal, the reciprocal is equal to your own 1, and the reciprocal is equal to your own only 0.
7. Scientific notation can be said to be a compulsory question in the senior high school entrance examination every year. When solving specific problems, we need to clearly remember related concepts; Also pay attention to unit conversion. For approximate numbers and precision, attention should be paid to the precision of numbers with calculation units, which need to be unified into numbers with "one" as calculation unit, and then determined.
8. Scientific notation can be said to be a compulsory question in the senior high school entrance examination every year. When solving specific problems, we need to clearly remember related concepts; Also pay attention to unit conversion. For approximate numbers and precision, attention should be paid to the precision of numbers with calculation units, which need to be unified into numbers with "one" as calculation unit, and then determined.
9. The comparison of real numbers is also a hot spot in the senior high school entrance examination. The main methods can be number axis comparison, estimation and difference. As for the law of reciprocity, the law of peace is not very common, and we just need to know it briefly.
10. Calculation is the basis of mathematics and the necessary means for us to solve problems. To improve the ability of real number operation, we must first examine the questions and understand the related concepts. Pay attention to zero exponent, negative integer exponent, multiplication, trigonometric function value of special angle, quadratic root simplification, absolute value and other knowledge points. When calculating, you need to determine the symbol first, then determine the result, and turn off the good symbol.
The above information is related to real numbers, and I hope it will be helpful to everyone.